The present invention relates to a hologram and, more particularly, to a Lippmann hologram which is reconstructible only with infrared or ultraviolet rays and hence suitable for security purposes.
It is a known practice to provide a hologram, which contains the record of a three-dimensional image symbol, pattern, etc., on a card or a bankbook, for example, as an integral part thereof in order to guarantee that the card or bankbook is genuine and it is not a forgery, and to reconstruct the hologram by illumination with specific reconstructing light to thereby verify that the card or bankbook is genuine.
However, most holograms used for such security purposes are simple diffraction grating patterns, image holograms, or Fresnel holograms. Therefore, these holograms can be readily reconstructed and read with simple illuminating light for reconstruction, and it is not always difficult to read and forge them.